Smart Contract Quick Start

This guide shows the minimal contract-side setup for integrating with Ring Swap (v2).

Ring Swap paths are FewToken-aware. If your user starts from an original ERC-20 asset, resolve the corresponding FewToken address before quoting or building a swap path. See the FewToken integration guide for the wrapping layer.

Choose the Target Chain

Start from the current Ring Swap deployments:

1. Select the target chain.
2. Copy the Ring Swap Router address.
3. Copy the Ring Swap Factory address if your contract needs to validate pairs or derive pair addresses.
4. Use the Ring Swap Pair Init Code for deterministic CREATE2 pair-address calculations.

Define the Minimal Interfaces

For simple swaps, most integrations only need the router interface:

pragma solidity ^0.8.20;

interface IRingSwapRouter {
    function WETH() external pure returns (address);

    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
}

For pair validation or reserve reads, use the pair and factory interfaces from the smart contract reference.

Approve and Swap

Your contract must hold the input tokens and approve the router before swapping:

pragma solidity ^0.8.20;

interface IERC20 {
    function approve(address spender, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

contract ExampleRingSwap {
    IRingSwapRouter public immutable router;

    constructor(address router_) {
        router = IRingSwapRouter(router_);
    }

    function swapExactInput(
        IERC20 inputToken,
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address recipient
    ) external returns (uint[] memory amounts) {
        require(inputToken.transferFrom(msg.sender, address(this), amountIn), 'transferFrom failed');
        require(inputToken.approve(address(router), amountIn), 'approve failed');

        return router.swapExactTokensForTokens(amountIn, amountOutMin, path, recipient, block.timestamp);
    }
}

Integration Notes

• Use FewToken addresses in Ring Swap paths when the pool is FewToken-native.
• Do not hardcode upstream deployment addresses. Ring deployments differ by chain.
• Price checks should come from an external quote, oracle, or SDK calculation before submitting the transaction.
• For deterministic pair addresses, prefer the Ring SDK helper when possible so chain-specific factory and init-code values stay aligned with the current deployment table.